@Override
 public View getView(int position, View convertView, ViewGroup parent) {
   if (position == getCount() - 1) {
     loadNextPage();
   }
   return imageFlowUtils.getView(
       position,
       convertView,
       parent,
       R.layout.item_gallery_image_line,
       R.layout.item_gallery_image,
       R.id.image,
       mImageWorker,
       getActivity());
 }
 @Override
 public void notifyDataSetChanged() {
   imageFlowUtils.rebuildGroups();
   super.notifyDataSetChanged();
 }
 @Override
 public Object getItem(int num) {
   return imageFlowUtils.getGroupItem(num);
 }
 @Override
 public int getCount() {
   return imageFlowUtils == null ? 0 : imageFlowUtils.getGroupsCount();
 }